Preparation of linear alpha olefin polymers having broad molecular weight distributions

ABSTRACT

Linear alpha olefin polymers having controlled broad molecular weight distributions are prepared by an improved process in which a zirconium catalyst composition, e.g., the reaction product of zirconium tetrachloride and aluminum triethyl, and another transition metal catalyst composition, e.g., the reaction product of vanadium oxytrichloride and aluminum triethyl, are introduced into a polymerization zone containing an alpha olefin in an inert organic solvent and the alpha olefin is subsequently polymerized at temperatures sufficient to maintain the resulting alpha olefin polymer in solution. Such alpha olefin polymers are found to have a wider variety of uses, e.g., from cable jacketing to bottle blowing applications, than alpha olefin polymers produced by conventional low pressure polymerization.

D United States Patent 1151 3,678,025 Birrell 1 1 July 18, 1972 [54]PREPARATION OF LINEAR ALPHA 3,066,126 11/1962 Porter et al. ..260/94.3

JS i i G BROAD FOREIGN PATENTS OR APPLICATIONS DISIRIBUTIONS 233%?251325 3 rea 11 am [72] Inventor: George B. Birrell, Eugene, Oreg.

Primary ExaminerJoseph L. Schofer [73] Asslgnee. :ii ch ChemicalCompany, Midland Assistant Examiner-Edward J. Smith 1 Attorney-Griswoldand Burdick, R. G. Waterman, L. J. Dan- [22] Filed: May 22, 1970 kertand M. S. Jenkins [2]] App]. No.: 39,890 [57] ABSTRACT Linear alphaolefin polymers having controlled broad molecu- [52] 1; lar weightdistributions are prepared by an improved process 51 1 Cl 6 6 6 in whicha zirconium catalyst composition, e.g., the reaction I93 7 B 94 9 Eproduct of zirconium tetrachloride and aluminum triethyl, and [58] he doarc another transition metal catalyst composition, e.g., the reactionproduct of vanadium oxytrichloride and aluminum [56] References Citedtriethyl, are introduced into a polymerization zone containing UNITEDSTATES PATENTS an alpha olefin in an inert organic solvent and the alphaolefin is subsequently polymerized at temperatures sufiicient to3,051,690 8/1962 Vandenberg ..260/88.2 maintain the resulting alpha l fipolymer in solution Such 3,073,811 1/1963 Notta et al ...260/93 7 alphal fi polymers are f d to have a wider variety f 13,1 15 l2/1963 Ziegleret a] 260/94 9 uses, e.g., from cable jacketing to bottle blowingapplications, 3,230,208 H1 COOKIE! at 3 than alpha olefin polymersproduced by conventional low 3,509,l l7 4/1970 Rust et al ressure polmerization 3,288,769 11/1966 Cooper et aL. "260/882 p y 3,308,l l23/1967 Ludlum ..260/94.9 14 Claims, No Drawings PREPARATION OF LINEARALPHA OLEFIN POLYMERS HAVING BROAD MOLECULAR WEIGHT DISTRIBUTIONSBACKGROUND OF THE INVENTION This invention relates to improved lowpressure polymerization processes for preparing alpha olefin polymershaving controlled broad molecular weight distributions.

The low pressure polymerization of alpha olefins with catalyst systemscomposed of a partially reduced, heavy transition metal component and anorganometallic reducing component to form high density, high molecularweight, solid, relatively linear polymers is well known.characteristically such polymerizations are carried out in an inertorganic liquid diluent under an inert atmosphere and at relatively lowtemperatures, e.g., to 100 C, and low pressures, e.g., 0 to 100 psig.Typical transition metal components are the halides, oxyhalides,alkoxides and the like of metals selected from Groups 4b, 5b, 6b and 8of the Periodic Table of Elements appearing in the Handbook of Chemistryand Physics, 48th ed., Chemical Rubber Company. Common organometalliccomponents include the metal alkyls, metal alkyl halides and dihalides,metal hydrides and similar compounds in which the metals are selectedfrom Groups la, 2a and 3a of the Periodic Table of Elements. The alphaolefin polymers produced by low pressure polymerization generally havemolecular weights in the range of about 100,000 to 300,000 or even ashigh as 3,000,000.

It is generally believed that the high molecular weight of the linearolefin polymer is primarily responsible for the polymers desirableproperties, e.g., strength, at relatively high temperatures.Unfortunately, however, these high molecular weight polymers have veryhigh viscosities at temperatures typically used in shaping suchpolymers, thus making the fabrication operation very difficult if notimpossible. As a result of this extreme difficulty of fabrication,shaped articles of such polymers such as wire cable jacketings, etc.,generally have objectionably rough surfaces and fissures which crackopen when subjected to stress. As a further disadvantage such polymersdo not have high swell ratios upon extrusion through a die, thus makingthe polymers undesirable for blow molding articles such as bottles, etc.Finally such high molecular weight polymers exhibit excessivebrittleness at low temperatures.

To overcome these problems which are generally though to be caused bythe low melt indexes of the high molecular weight linear polymers, ithas been a common practice in the art to alter the conditions of themetal-catalyst polymerization processes in order to increase the amountof low molecular weight polymer formed. In accordance with somepractices, molecular weights of the resulting linear polymers arelowered by varying conditions during polymerization such as temperature,pressure, amount of diluent and concentration of catalyst. In moresophisticated methods, molecular weight of such polymers are lowered byadding hydrogen to the reaction vessel during polymerization.

Although lowering the average molecular weight of the linear polymer byone of the above techniques generally facilitates fabrication, it alsocauses a loss in physical properties such as strength at hightemperatures. As a'result the polymer, once fabricated, is easier todistort, tear, break, etc., than the higher molecular weight polymers.

In view of the aforementioned deficiencies in linear olefin polymersprepared by the prior art methods, it would be highly desirable toprovide a polymerization process for producing linear olefin polymershaving both the strength of the high molecular weight polymers and thegood processability of the low molecular weight polymers.

SUMMARY OF THE INVENTION In accordance with this invention linear olefinpolymers having both improved processability and improved strength areprepared by an improved process for polymerizing in a polymerizationzone an alpha olefin in an inert organic diluent in the presence of acatalytic amount of a catalyst composition formed by reacting anorganometallic compound with a compound of transition metal of thefourth period of the Periodic Table of Elements. The improvementcomprises the steps of (l) introducing into the polymerization zone, inaddition to the above named catalyst, a sufficient amount of azirconiumcontaining catalyst composition which is the reaction productof a metal alkyl component with a zirconium compound to give atransition metal/zirconium molar ratio ranging from about 05:1 to about10:! and (2) polymerizing the alpha olefin at temperatures and pressuressufficient to maintain the resulting linear olefin polymer dissolved inthe liquid diluent.

By linear" polymer is meant that the backbone chain of the macromoleculeis substantially non-crosslinked and nonbranched, i.e., linear, andincludes polymers such as isotactic polymers of propylene, higherl-alkenes, styrene, etc., wherein the linear main chain has substituentgroups attached thereto arising from the substituted ethylene monomer.Also, as used herein, the term olefin polymers" is meant to includehomopolymers, copolymers and interpolymers of alpha olefins.

Linear olefin polymers prepared in accordance with this improved processhave relatively broad molecular weight distributions. As a consequenceof broad molecular weight distribution, these polymers have muchimproved processability, particularly at high shear rates which aretypical in extrusion. Surprisingly, however, such polymers also havestrength at high temperatures equivalent to that of polymers havinghigher molecular weight averages, but narrower molecular weightdistributions. As further advantages, these linear polymers tend toexhibit increased swell upon extrusion through a die and have improvedstress crack resistance at both high and low temperatures.

Such polymers are very useful in the fabrication of shaped articles suchas cable jacketing, bottles, containers, sheets,

films and the like. Such polymers also can be molded by compression orinjection techniques to form a wide variety of other articles.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The improvement of the presentinvention is employed in a low pressure polymerization process whereinan alpha olefin is polymerized, advantageously in the presence ofhydrogen, in a polymerization zone containing an inert diluent and atwocomponent metal catalyst composition of a type commonly known as aZiegler-Natta catalyst.. Such low pressure processes are commonlycarried out under an inert atmosphere and at relatively low temperatureand pressure.

Olefins which are suitably polymerized or copolymerized are generallythe alpha olefins having from two to 18 carbon atoms. Illustratively,such alpha olefins include ethylene, propylene, butene-l, pentene-l,3-methylbutene-l, 4-methylbutene-l, hexene-l, octene-l, decene l,dodecene-l, octadecene-l, and the like. It is understood that such alphaolefins may be copolymerized with other alpha olefins and/or with smallamounts, i.e., up to about 10 weight percent based on the polymer, ofother ethylenically unsaturated monomers such as butadiene, isoprene,pentadiene-l,3, styrene, amethyl styrene, ar-methyl styrene, and thelike.

The two component metal catalyst composition is the reaction product of(1) an organometallic reducing compound corresponding to the formulaMR,,X,, wherein M is a metal of Group la, 2a, or 3a of the PeriodicTable of Elements, R is an alkyl group having from one to eight carbonatoms, X is hydrogen or halogen, and n m is a positive whole numbercorresponding to the number of valence electrons of M wherein n =1, 2 or3 and m =0, l or 2 and (2) a compound of transition metal other thanzirconium as specified hereinafter. The reaction product advantageouslyhas a molar ratio of Mztransition metal ranging from about 0.5:1 toabout 5:1, preferably from about 0.5: l to 2:1.

Examples of MR,,X,,, include the aluminum trialkyls, e.g., aluminumtriethyl, aluminum triisobutyl, aluminum tripropyl, aluminum diethylpropyl, and other aluminum trialkyls wherein alkyl has from one to eightcarbon atoms; aluminum alkyl hydrides, e.g., aluminum diethyl hydrideand aluminum isobutyl dihydride; aluminum alkyl halides, e.g.,diethylaluminum chloride, diethylaluminum bromide, ethylaluminumdichloride and the like; magnesium dialkyls; zinc dialkyls; alkali metalalkyls and hydrides; alkali metal aluminum hydrides; and other hydridesand alkyls of Group 1, 2 and 3 metals wherein the alkyl groups containone to eight carbon atoms. Preferred MR,,X,,, are the aluminumtrialkyls, especially aluminum triethyl and aluminum triisobutyl, andthe aluminum alkyl halides, especially diethylaluminum chloride.

Representative reducible transition metal compounds include the halides,oxyhalides, alcoholates, alkoxides and esters of the Group 4b, 5b, 6b,7b and 8 metals ofthe fourth period of the Periodic Table of Elements,i.e., titanium, vanadium, chromium, iron, manganese, cobalt and nickel.Examples of such components include reducible titanium halides such astitanium tetrachloride, titanium trichloride, titanium tetrabromide,titanium tetraiodide and the like; reducible vanadium halides andoxyhalides such as vanadium pentachloride and vanadium oxytrichloride;titanium tetramethoxide, titanium triethoxide, tripropoxy-titaniumchloride, titanium acetylacetonate, titanium tetraacetate, chromiumacetylacetonate, iron acetylacetonate and similar compounds of the abovementioned transition metals. Preferred transition metal compounds aretitanium tetrachloride, titanium trichloride and vanadiumoxytrichloride.

While the catalyst reaction product can be prepared in a variety ofprocedures, a simple and an effective method is to add the transitionmetal component to the organometallic reducing component, or vice versa,preferably in the presence of an inert organic solvent. By way ofexample ofsuitable inert organic solvents can be mentioned liquefiedethane, propane, isobutane, normal butane, n-hexane, the variousisomeric hexanes, isooctane, cyclohexane, methylcyclopentane,dimethylcyclohexane, dodecane, industrial solvents composed of saturatedand/or aromatic hydrocarbons, such as kerosenes, naphthas, etc.,especially when freed of any olefin compounds and other impurities, andespecially those ranging in boiling point up to 600 F. Also included arebenzene, toluene, ethylbenzene, cumene, decalin, and the like.

in low pressure processes, i.e., usually up to about 100 atmospheres,polymerization is effected by adding a catalytic amount of the abovereaction product to a polymerization zone containing monomer, or viceversa, and subsequently heating the zone to temperatures ranging from 40to 250 C. It is generally desirable to carry out polymerization inabsence of moisture and air. Catalytic amounts of the reaction productcan range from as low as 0.01 weight percent based on total weight ofmonomers charged to as high as weight percent. While preferred amountsvary with the polymerization conditions such as temperature, pressure,solvent, presence of catalyst poisons, etc., generally preferredconcentrations of the reaction product range from 0.1 up to about 1weight percent.

Hydrogen is often employed in low pressure polymerization processes tolower the molecular weight of the result polymer. For the purposes ofthis invention, it is beneficially employed in concentrations rangingfrom about 0.001 to about 0.5 mole per mole of monomer. The largeramounts of hydrogen within this range are found to produce generallylower molecular weight polymers. It is to be understood that hydrogencan be added with the monomer stream to the polymerization vessel orseparately to said vessel before, during or after addition of themonomer to the polymerization vessel. It should be noted, however, thatthe presence of hydrogen in conventional low pressure polymerizationlowers molecular weight average of polymer and does not affect molecularweight distribution.

The improvement of the present invention comprises the steps of l)introducing into the polymerization zone, in addition to the transitionmetal catalyst composition, a sufiicient amount of a zirconium catalystcomposition to yield a transition metal/zirconium molar ratio rangingfrom about 0.5:1 to about 10:1 and (2) polymerizing the alpha olefin attemperature and pressure sufficient to maintain the resulting alphaolefin polymer in solution. Temperatures and pressures sufficient tomaintain the polymer dissolved in an inert solvent or unreacted monomergenerally range from about to about 300 C and from about 0 to about1,500 pounds per square inch gauge (psig) respectively; preferably fromabout to about C and from about 100 to about 1,000 psig.

To obtain maximum breadth of molecular weight distribution in theresulting polymer, a transition metal/zirconium molar ratio rangingbetween about 0.521 to about 10:1 is desired, preferably 0.5:1 to 7:1.At lower ratios of transition metal to zirconium, larger amounts of thevery high molecular weight polymer are formed. Such polymer products areexceptionally suited for wire and cable applications. At the higherratios of transition metal to zirconium, the higher molecular weightportion is reduced in proportion and the resultant product isparticularly suited to blow molding and the like. Of particularimportance, however, is the fact that substantial portions of both veryhigh and low molecular weight polymer are formed at all transitionmetal/zirconium molar ratios within the specified range of 0.521 and 10:1.

The zirconium catalyst composition is a reaction product of (1) a metalalkyl component having the formula MR,,X,,, wherein M, R, X, n and m areas described hereinbefore and (2) a zirconium compound, preferably ahalide or oxyhalide of zirconium. The molar ratio of M to zirconiumadvantageously ranges from about 0.521 to about 5:1, preferably fromabout 1:1 to about 2:1. At M:zirconium ratios below 05:] low molecularweight polymer is primarily produced. Above 5:1 the polymer yields aresomewhat low.

Examples of MR,,X,,, suitable for reaction with the zirconium compoundare generally those metal alkyls set forth hereinbefore. For thisreaction, MR,,X,,, is preferably aluminum trialkyl such as aluminumtriethyl and aluminum triisobutyl. It is understood that MR,,X,,, neednot be the same in the transition metal and zirconium catalystcompositions although it may be.

Preferred zirconium compounds include the trihalides and tetrahalides ofzirconium, e.g., zirconium tetrachloride and trichloride, zirconiumtetrabromide and tribromide, zirconium tetrafluoride and trifluoride,and zirconium tetraiodide and triiodide; and the oxyhalides ofzirconium, e.g., zirconylchloride, zirconylbromide and the like. Theprocedural steps of the methods for preparing the zirconium catalystcomposition are essentially the same as for preparing the abovedescribedtransition metal catalyst compositions and are not described further forthat reason.

Both the transition metal catalyst composition and the zirconiumcatalyst composition are sensitive to various poisons, among which maybe mentioned oxygen, carbon dioxide, carbon monoxide, acetyleniccompounds such as acetylene, vinylacetylene, and the like. For thisreason, suitable precautions should be taken to protect the catalystcompositions and the polymerization mixture from excessive contact withsuch materials. The monomers and diluents or solvents, if used, need notbe pure so long as they are reasonably free from poisons. It isdesirable to protect both of the catalyst compositions duringpreparation, storage, and use by blanketing with an inert gas, e.g.,nitrogen, argon, or helium,

The monomer or mixture of monomers is contacted with the transitionmetal and zirconium catalyst compositions in any convenient manner,preferably by bringing the catalyst compositions and monomer togetherwith intimate agitation provided by suitable stirring or other means. Itis understood that the zirconium catalyst composition can be introducedprevious to or simultaneous with introduction of the transition metalcatalyst composition prior to polymerization, subsequent to introductionof the transition metal catalyst composition during polymerization, orportions of the zirconium catalyst composition can be introduced bothsimultaneous with and subsequent to introduction of the transition metalcomposition.

Agitation can be continued during the polymerization, or in someinstances, the polymerization mixture can be allowed to remain quiescentwhile the polymerization takes place. In the case of the more rapidreactions with the more active catalysts, means can be provided forrefluxing monomer and solvent, if any of the latter is present, and thusremove the heat of reaction. In any event, adequate means should beprovided for dissipating the exothermic heat of polymerization. Ifdesired, the monomer can be brought in vapor phase into contact withsolid catalyst, in the presence of or absence of liquid solvent. Thepolymerization can be efiected in the batch manner, or in a continuousmanner, such as, for example, by passing the reaction mixture through anelongated reaction tube which is contacted externally with suitablecooling medium to maintain desired reaction temperature; or by passingthe reaction mixture through an equilibrium overflow reactor, or aseries of the same.

The polymer can be recovered from the total reaction mixture by a widevariety of procedures, chosen in accordance with the properties of theparticular polymer, the presence or absence of solvent, and the like. Itis generally quite desirable to remove as much catalyst from the polymeras possible, and this is conveniently done by contacting the totalreaction mixture or the polymer after separation from solvent, etc.,with methanolic hydrochloric acid, with an aliphatic alcohol such asmethanol, isobutanol, secondary butanol, or by various other procedures.If the polymer is insoluble in the solvent at lower temperatures, it canbe separated therefrom by filtration, centrifuging or other suitablephysical separation procedure. If the polymer is soluble in the solvent,it is advantageously precipitated by admixture of the solution with anon-solvent, such non-solvent usually being an organic liquid misciblewith the solvent but in which the polymer to be recovered is not readilysoluble. Of course, any solvent present can also be separated frompolymer by evaporation of the solvent, care being taken to avoidsubjecting the polymer to too high a temperature in such operation. If ahigh boiling solvent is used, it is usually desirable to finish anywashing of the polymer with a low boiling material, such as one of thenitrogen is made into a slurry by the addition of m1 of isooctane (driedover CaH and deaerated). A 5-ml portion of a 1 molar solution ofaluminum triethyl in isooctane is then added to the slurry therebyconverting the white zirconium tetrachloride to a brown solid(Al:Zr=2:1). A transition metal catalyst composition is prepared byadding 5 mls of 0.5 molar solution of vanadium oxytrichloride and 5 mlsof L0 molar solution of aluminum triethyl (Al:V=2:l) in isooctane to avessel under nitrogen and containing 40 mls of isooctane. Two

liters of isooctane (deaerated and dried) is introduced into a onegallon stirred polymerization reactor containing nitrogen and is heatedto 150 C. The reactor is vented to approximately 25 psig and 13 psig ofhydrogen is added. The reactor is then filled with ethylene to obtain areactor pressure of 148 psig and ethylene pressure is set at theethylene source to maintain a pressure of 148 psig throughout thereaction. A 20- ml portion of the zirconium catalyst composition and al0-ml portion of the vanadium catalyst composition are charged to thereactor, and the reaction temperature is maintained at 150 C for aperiod of minutes. The reaction is stopped and 70.7 grams of the polymerare recovered, washed with alcohol and dried. The 1 and 1 values of thepolymer are measured and the /l ratio are calculated. The results areshown in Table I.

To further exemplify the invention, several polymerization runs (ExampleNos. 2, 3 and 4) are carried out essentially according to the abovegeneral procedure except that different ratios of the zirconium catalystcomposition and the vanadium composition are employed. The 1 and 1values and l ll, ratios of the resulting polymers are determined and arealso recorded in Table I.

For the purposes of comparison and to particularly point out theadvantages of the present invention, two control runs (C and C arecarried out polymerizing ethylene in the presence of hydrogenessentially according to the conditions of Example 1. in C however, theonly catalyst added to the polymerization recipe is a 20 ml-portion ofthe zirconium catalyst composition of Example 1. in C, the only catalystemployed is a 20 ml-portion of the vanadium catalyst composition ofExample I. The resulting polymer is recovered and the 1 and l values andl ll ratios are determined and recorded in Table l.

TABLE I Catalyst concentration, Pressure, p.s.i.g. Ti/Zr, millimole I1,I10, mole decigJ dccig. Example No. Catalyst 1 C2114 II; Total ratio ZrTi min min. ImII- 1 ZrCh-ATE-l-VOCh-ATE 110 13 148 0. 5:1 1.0 0. 5 0. 121.75 14. G 2 ZrCh-ATE-l-VOClrATE 110 13 148 1 1 0, 75 0. 75 0. 32 5. 8518. .5 3 ZrCl4-A'IE+VOCl -ATE 108 10 146 6 1 0.25 0. 75 6. 72 96. 2 14,3 4 ZrClrATE-l-VOCli-ATE 103 10 148 7 1 0.125 0.875 0. 68 108 11. 2 C TE104 13 144 1. 0 0. 04 0. 42 10. 5 104 13 144 1. 0 100 8, 500 -8. 5

l ATE =Alu1ninum triethyl.

lower aliphatic alcohols or hexane, pentane, etc., which aids removal ofthe higher boiling materials and permits the maximum removal ofextraneous material during the final polymer drying step. Such dryingstep is desirably effected at reduced pressure at temperatures below 300C.

The following examples are given to illustrate the invention and shouldnot be construed as limiting its scope. All parts and percentages are byweight unless otherwise indicated. The symbols and l represent the meltflow viscosity in deci grams/minute of the polymer measured according toASTM D-l238-5T(E) and ASTM D-l238-65T(N), respectively. The l ll ratiois a practical measure of the breadth of the molecular weightdistribution of the polymer with larger ratios indicating broadermolecular weight distributions.

EXAMPLES l-4 Not an example of the invention.

As evidenced by the l ll ratios of Table I, the polyethylenes preparedby the improved process of this invention have substantially broadermolecular weight distributions than those prepared by using either ofthe zirconium or vanadium catalyst compositions alone.

EXAMPLE 5 Ethylene is polymerized according to Example 1 except thattitanium tetrachloride-aluminum triethyl (Al:Ti=2:1) is substituted forvanadium oxytrichloride-aluminum triethyl. The polymer is recovered andthe 1 and 1 values and 1 /1 ratio are determined and recorded in Table11.

For the purposes of comparison a control run (C is carried outessentially according to Example 5 except only the titanium catalystcomposition is employed as the catalyst. The polymer is recovered andtested and results are recorded in A 0.582-gram portion of zirconiumtetrachloride under Table II.

As evidenced by the l /l ratios in Table II, the polymer prepared by theimproved process of this invention exhibited a broader molecular weightdistribution than the polymer prepared by employing only the titaniumcatalyst composihydrides, and aluminum alkyl halides wherein alkyl hasfrom one to eight carbon atoms and halide is chloride or bromide with areducible compound of a transition metal selected from the groupconsisting of titanium and vanadium; the improveri ment according toclaim 11 which comprises (1) introducing TABLE I[ Catalystconcentration, Pressure, p.s.i.g. 'Ii/Zr, millimole I2, I10, molardecig./ deeigJ Example N0. Catalyst 02H; Hz Total ratio Zr Ti min. min.Ito/I: 5 ZrCh-A'IE --1TiCl4-AIE 1 102 20 148 0. 5/1 1.0 0. 5 2. 08 30. 914,3 0 TiCli-AIE l 1 2 0 148 1.0 0.40 4. 25 10.6

1 ATE=Aluminum triethyl. Not an example of the invention.

What is claimed is:

1. In a process for polymerizing in a polymerization zone an alphaolefin having from two to 18 carbon atoms in the presence of a catalyticamount of a transition metal catalyst composition formed by reacting anorganometallic reducing compound corresponding to the formula MR,,X,,,wherein M is a Group la, 2a or 3a metal of the Periodic Table ofElements, R is hydrogen or an alkyl group having from one to eightcarbon atoms, X is halogen, n m is a positive whole number correspondingto the number of valence electrons of M, n is 1, 2 or 3 and m is 0, 1 or2, with a reducible compound of titanium or vanadium; the improvementwhich comprises l) introducing into the polymerization zone, in additionto said transition metal catalyst composition, a sufficient amount ofazirconium catalyst composition which is a reaction product of (a) anorganometallic reducing compound corresponding to the formula MR X,where M is a Group 1a, 2a or 3a metal, R is hydrogen or an alkyl grouphaving from one to eight carbon atoms, X is. halogen, n m is a positivewhole number corresponding to the number of valence electrons of M, n isl, 2 or 3 and m is 0, 1 or 2 with (2) a reducible zirconium compound toyield a reducible compound/zirconium molar ratio ranging from about0.5:1 to about :1 and (2) polymerizing the alpha olefin at temperaturesand pressures sufficient to maintain the resulting polymer in solutionthereby providing an alpha olefin polymer having broad molecular weightdistribution.

2. The improvement according to claim 1 wherein the zirconium compoundis zirconium tetrachloride.

3. The improvement according to claim 1 wherein hydrogen is present inconcentration in the range of from about 0.001 to about 0.5 mole permole of the alpha olefin.

4. The improvement according to claim 1 wherein MR X of the transitionmetal catalyst composition is an aluminum trialkyl.

5. The improvement according to claim 1 wherein the reducible compoundis a reducible titanium halide.

6. The improvement according to claim 1 wherein the reducible compoundis a reducible vanadium oxyhalide.

7. The improvement according to claim 1 wherein MR,,X,,, ofthe zirconiumcatalyst composition is an aluminum trialkyl.

8. The improvement according to claim 1 wherein the temperature iswithin a range from about 130 to about 300 C.

9. The improvement according to claim 1 wherein the pressure is within arange from about 100 to about 1,000 psig.

10. The improvement according to claim 1 wherein the reduciblecompound/zirconium molar ratio is within a range from about 0.5:1 toabout 7:1.

11. The improvement according to claim 1 wherein the molar ratio oftitanium or vanadium to M of the transition metal catalyst compositionranges from about 0.5:] to about 5:1 and the molar ratio of zirconium toM of the zirconium catalyst composition is about 0.5:] to about 5:1.

12. In a process for polymerizing in a polymerization zone an alphaolefin selected from the group consisting of ethylene, propylene andbutene-l in the presence of a catalytic amount of a transition metalcatalyst composition formed by reacting an organometallic reducingcompound selected from the group consisting of aluminum trialkyls.aluminum alkyl into the polymerization zone, in addition to saidtransition metal catalyst composition, a sufficient amount of azirconium catalyst composition which is a reaction product of (a) anorgano-metallic reducing compound selected from the group consisting ofaluminum trialkyls, aluminum alkyl hydrides and aluminum alkyl halideswherein alkyl has from one to eight carbon atoms and halide is chlorideor bromide with (b) a reducible zirconium compound to yield a transitionmetal/zirconium molar ratio ranging from about 0.5:1 to about 10:1 and2) polymerizing the alpha olefin in the presence of from about 0.001 toabout 0.5 mole of hydrogen per mole of alpha olefin at temperatures andpressures sufficient to maintain the resulting polymer in solutionthereby providing an alpha olefin polymer having broad molecular weightdistribution.

13. In a process for polymerizing ethylene in the presence of acatalytic amount of a transition metal catalyst composition formed byreacting aluminum triethyl with a reducible transition metal compoundselected from the group consisting of titanium tetrachloride andvanadium oxychloride; the improvement according to claim 11 whichcomprises (1) introducing into the polymerization zone, in addition tosaid transition metal catalyst composition, a sufficient amount of azirconium catalyst composition which is a reaction product of (a)aluminum triethyl with zirconium tetrachloride to yield a transitionmetal/zirconium molar ratio ranging from about 0.5:1 to about 10:1 and(2) polymerizing the alpha olefin in the presence of from about 0.001 toabout 0.5 mole of hydrogen per mole of alpha olefin at temperatures andpressures sufficient to maintain the resulting polymer in solutionthereby providing an alpha olefin polymer having broad molecular weightdistribution.

14. In a process for polymerizing in a polymerization zone an alphaolefin selected from the group consisting of ethylene, propylene andbutene-l in the presence of a catalytic amount of a transition metalcatalyst composition formed by reacting an organometallic reducingcompound selected from the group consisting of aluminum trialkyls anddiethyl aluminum chloride one to eight carbon atoms with a reduciblecompound ofa transition metal selected from the group consisting oftitanium and vanadium wherein the aluminum/transition metal molar ratiois in the range from about 0.521 to about 5:1; the improvement accordingto claim 11 which comprises l introducing into the polymerization zone.in addition to said transition metal catalyst composition, a sufiicientamount ofa zirconium catalyst composition which is a reaction product of(a) an organometallic reducing compound selected from the groupconsisting of aluminum trialkyls, and diethyl aluminum chloride whereinalkyl has from 1 to 8 carbon atoms with (b) a reducible zirconiumcompound wherein the aluminum/zirconium molar ratio is in the range fromabout 0.511 to about 5:1 to yield a transition metal/zirconium molarratio ranging from about 0.511 to about 10:1 and (2) polymerizing thealpha olefin in the presence of from about 0.001 to about 0.5 mole ofhydrogen per mole of alpha olefin at temperatures and pressuressufficient to maintain the resulting polymer in solution therebyproviding an alpha olefin polymer having broad molecular weightdistribution.

Patent No. 3,678,025 Dated 18 July 1 Natal-(B) George B. Birrell It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column l, line 46,- change "though" to "thought";

Column 7, line 36, delete "(2)" and insert (b)--.

Column 8, line 53, insert -wherein alkyl has frombetween the words"chloride" and "one".

Signed and sealed this 9th day of January 1973.

(SEAL) Attest:

EDWARDMJLETCHERJR. ROBERT GOTTSCHAL K Attesting Offieer Commissioner ofPatents

2. The improvement according to claim 1 wherein the zirconium compoundis zirconium tetrachloride.
 3. The improvement according to claim 1wherein hydrogen is present in concentration in the range of from about0.001 to about 0.5 mole per mole of the alpha olefin.
 4. The improvementaccording to claim 1 wherein MRnXm of the transition metal catalystcomposition is an aluminum trialkyl.
 5. The improvement according toclaim 1 wherein the reducible compound is a reducible titanium halide.6. The improvement according to claim 1 wherein the reducible compoundis a reducible vanadium oxyhalide.
 7. The improvement according to claim1 wherein MRnXm of the zirconium catalyst composition is an aluminumtrialkyl.
 8. The improvement according to claim 1 wherein thetemperature is within a range from about 130* to about 300* C.
 9. Theimprovement according to claim 1 wherein the pressure is within a rangefrom about 100 to about 1,000 psig.
 10. The improvement according toclaim 1 wherein the reducible compound/zirconium molar ratio is within arange from about 0.5:1 to about 7:1.
 11. The improvement according toclaim 1 wherein the molar ratio of titanium or vanadium to M of thetransition metal catalyst composition ranges from about 0.5:1 to about5:1 and the molar ratio of zirconium to M of the zirconium catalystcomposition is about 0.5:1 to about 5:1.
 12. In a process forpolymerizing in a polymerization zone an alpha olefin selected from thegroup consisting of ethylene, propylene and butene-1 in the presence ofa catalytic amount of a transition metal catalyst composition formed byreacting an organometallic reducing compound selected from the groupconsisting of aluminum trialkyls, aluminum alkyl hydrides, and aluminumalkyl halides wherein alkyl has from one to eight carbon atoms andhalide is chloride or bromide with a reducible compound of a transitionmetal selected from the group consisting of titanium and vanadium; theimprovement according to claim 11 which comprises (1) introducing intothe polymerization zone, in addition to said transition metal catalystcomposition, a sufficient amount of a zirconium catalyst compositionwhich is a reaction product of (a) an organo-metallic reducing compoundselected from the group consisting of aluminum trialkyls, aluminum alkylhydrides and aluminum alkyl halides wherein alkyl has from one to eightcarbon atoms and halide is chloride or bromide with (b) a reduciblezirconium compound to yield a transition metal/zirconium molar ratioranging from about 0.5:1 to about 10:1 and (2) polymerizing the alphaolefin in the presence of from about 0.001 to about 0.5 mole of hydrogenper mole of alpha olefin at temperatures and pressures sufficient tomaintain the resulting polymer in solution thereby providing an alphaolefin polymer having broad molecular weight distribution.
 13. In aprocess for polymerizing ethylene in the presence of a catalytic amountof a transition metal catalyst composition formed by reacting aluminumtriethyl with a reducible transition metal compound selected from thegroup consisting of titanium tetrachloride and vanadium oxychloride; theimprovement according to claim 11 which comprises (1) introducing intothe polymerization zone, in addition to said transition metal catalystcomposition, a sufficient amount of a zirconium catalyst compositionwhich is a reaction product of (a) aluminum triethyl with zirconiumtetrachloride to yield a transition metal/zirconium molar ratio rangingfrom about 0.5:1 to about 10: 1 and (2) polymerizing the alpha olefin inthe presence of from about 0.001 to about 0.5 mole of hydrogen per moleof alpha olefin at temperatures and pressures sufficient to maintain theresuLting polymer in solution thereby providing an alpha olefin polymerhaving broad molecular weight distribution.
 14. In a process forpolymerizing in a polymerization zone an alpha olefin selected from thegroup consisting of ethylene, propylene and butene-1 in the presence ofa catalytic amount of a transition metal catalyst composition formed byreacting an organometallic reducing compound selected from the groupconsisting of aluminum trialkyls and diethyl aluminum chloride one toeight carbon atoms with a reducible compound of a transition metalselected from the group consisting of titanium and vanadium wherein thealuminum/transition metal molar ratio is in the range from about 0.5:1to about 5:1; the improvement according to claim 11 which comprises (1)introducing into the polymerization zone, in addition to said transitionmetal catalyst composition, a sufficient amount of a zirconium catalystcomposition which is a reaction product of (a) an organometallicreducing compound selected from the group consisting of aluminumtrialkyls, and diethyl aluminum chloride wherein alkyl has from 1 to 8carbon atoms with (b) a reducible zirconium compound wherein thealuminum/zirconium molar ratio is in the range from about 0.5:1 to about5:1 to yield a transition metal/zirconium molar ratio ranging from about0.5:1 to about 10:1 and (2) polymerizing the alpha olefin in thepresence of from about 0.001 to about 0.5 mole of hydrogen per mole ofalpha olefin at temperatures and pressures sufficient to maintain theresulting polymer in solution thereby providing an alpha olefin polymerhaving broad molecular weight distribution.